Research is proposed to use virus mediated cell transformation to generate permanent cell lines of pancreas endocrine cells which have conditional ability to express differentiated endocrine function. This will be accomplished by infecting neonatal rat pancreas monolayer cultures with temperature sensitive mutants of simian virus 40. Mutants in the A cistron of this virus are expected to produce cell lines which display temperature dependent proliferative capacity. Screening methods are being developed to select those cell lines which have the ability to produce specific hormones. In addition, transformed cells are being implanted into immune-deficient mice to evaluate the biological activity of these cells in vivo. The proposed research could provide homogeneous populations of pancreatic endocrine cell types in sufficient quantity for many experiments not now possible.